Needle plate or throat plate for chain stitch sewing machines



Aprii 1967 H. F. DANIEL ETAL 3,313,259

NEEDLE PLATE OR THROAT PLATE FOR CHAIN STITCH SEWING MACHINES Filed Feb. 23, 1965 IGi. i I 5 m I! J m Min "IIIJIIIMIIIIIHHIW INVENTORS HERMANN F. DANIEL c2" EUGEN ANGE LE United States Patent 3,313,259 NEEDLE PLATE GR THROAT PLATE FOR CHAIN STITCH SEWING MACHINES Hermann 35. Daniel and Eugen Angela, Stuttgart, Germany, assignors to Union Special Maschinenfabrik G.m.b.II., Stuttgart, Germany Filed Feb. 23, 1965, Ser. No. 434,368 Claims priority, application Germany, Mar. 12, 1964, U 10,534 15 Claims. (Cl. 112260) The invention is concerned with a needle plate or throat plate and presser foot arrangement for chain stitch sewing machines.

In the case of chain stitch sewing machines, in contrast to lock stitch sewing machines, the hanging loop of the needle thread is tightened only after the next descent of the needle. In order to achieve this tightening of the hanging loop of the needle thread, the needle hole of the throat plate in the case of chain stitch sewing machines has been enlarged at least to the length of a stitch as a slot and extending in the feeding direction.

Such enlargement of the needle hole is feasible only so long as there is only one feed direction, or two definite and aligned feed directions for the material. But if one is to sew with such a sewing machine in all directions of the sewing plane, then it would be necessary to enlarge the needle hole in all directions by a stitch length. In such an arrangement, however, the needle hole would be relatively large and the material would not be held securely in position and would flag or flutter as the needle passes in and out of the material. As a result, one would not achieve a faultless formation of the loop of the needle thread for entrance by the looper point, and even tightening of the thread would not be achieved.

The present invention has for its purpose to provide means permitting sewing with a chain stitch sewing machine in any desired direction of the sewing plane, and primarily to develop a novel form of throat plate or needle plate and presser foot constructed and arranged in such a manner that faultless formation of stitches will be possible in any desired sewing direction.

More specifically, the novel throat plate is characterized by the fact that the needle hole consists of a number of slots extending in the form of rays around the path of the needle and opening radially outwardly from its center. By reason of these slots extending ray-shaped or radially about the path of the needle, the sewing threads will extend into one of these slots in any desired feed direction, thus to assure that a perfect tightening of the thread will be achieved when forming the stitch. On the other hand, the prongs or connecting portions extending inward between the slots form rests on which the cloth is supported, and as a result, fluttering of the cloth will be prevented during the formation of the stitches. The free ends of the prongs are rounded in order to make it easier for the threads to slide off said ends into one of the radial slots. A further essential development of the needle plate has been characterized in that the central opening of the needle hole, which has been framed by the free ends of the prongs, has been enlarged on the underside of the needle plate.

In the formation of chain stitches and feeding of the material or cloth in all directions in the sewing plane, use is made of a loop spreader element which directs the threads in a certain direction in order to offer to the needle an open triangle constituted by the threads. The strands of thread extending from the spreader element to the cloth may cross the path of the needle in some of these feeding possibilities. In this case the needle, besides entering the spread out triangle formed by the threads, might also pierce through and break one or more 3,313,259 Patented Apr. 11, 1957 See of the strands of the thread reaching from the spreader to the cloth. In order to avoid this, a further characteristic of the invention consists in disposing the prongs at the needle hole of the throat plate so that one thereof is always aligned with a line which at the entry of the needle into the throat plate or needle plate extends from the acting point of a spreader along the threads through the path of the needle. Through such an arrangement of the prongs, if the cloth to be sewed is moved in a predetermined feed direction in which the strands of thread extending from the spreader to the cloth would have to cross the path of the needle, said strands, through tightening of the threads, are forced aside into one of the slots located beside the prongs and will thus lie beside the path of the needle and will not be pierced 'by the needle.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawing.

In the drawing:

FIGURE 1 shows a longitudinal section through a throat plate or needle plate with a presser foot located above it, as well as a needle, a looper and a loop spreader.

bFIGURE 2 shows the same arrangement viewed from a ove.

The figures show the formation of the stitch at that point where the needle enters the spread out triangle formed by the threads and, there being illustrated a feed direction which extends from the acting point of a spreader in the direction of the path of the needle and which is indicated by an arrow A. The needle thread 2 hangs on the looper 1 as a result of the previous entry by the needle, and this loop together with the looper thread 3 forms a triangle which has been widened by the spreader 4, so that the needle 5 could enter therein.

A presser foot 6 presses the layers 7 of cloth which are to be sewn together against a throat plate or needle plate 8. According to the present invention, this needle plate has been provided with a needle hole 9 from which slots 10 radiate outwardly from the center thereof as clearly shown in FIGURE 2. The prongs 11, which remain between the slots, frame the actual needle hole 9 and are rounded off in the plane of the needle plate at their inwardly directed end extremities. Downward the needle hole 9 has been enlarged to provide an underside or bottom face recess 9a as shown in FIGURE 1. It will be apparent by reference to FIGURE 2 that the slots have been arranged in such a manner that one of the prongs, designated 11a in said figure, extends opposite to the direction of the arrow A in alignment with a line defined by an acting point 15 on spreader 4 and the center of the needle 5. As a result, the threads which extend from the spreader 4 at the acting point 15 to the material or cloth are forced away during the feed, this forcing away being in the general direction of the arrow A and slip into one of the slots located beside the prong 11a, and by reason of this fact the needle 5 will pass by to one side of these threads without piercing any of the strands thereof. At the same time, one must take into consideration the fact that it will be sufiicient if the threads are forced away in this direction as far as is necessary for the point of the needle to just miss them, so that the needle during its further downward movement will force the threads farther to one side.

It will be apparent by reference to FIGURE 1 that the presser foot 6 is disposed with its needle hole 12 directly overlying and centered over the throat plate needle hole 9. The needle hole 12 of the presser foot includes a cylindrical lower portion 13 and a conically widened or upwardly flaring upper or needle receiving portion 14. As

a will be observed, the hole portion 13 is not much larger in diameter than the diameter of the needle This particular formation and placement of the presser foot needle hole provides notable advantages in combination with the throat plate needle hole structure. It has been found that commonly known needle guards and presser feet will not prevent bending of the needle and resulting skip and miss stitches on automatic units, as the work may be fed in any direction over 360. The particular small form of needle hole and the arrangement thereof here stressed serves to prevent bending of the needle.

While preferred part structure and arrangement has been disclosed in detail herein, it is to be understood that variations in and departures from the specific disclosures may be made without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. A needle plate for chain stitch sewing machines having a needle hole formed therein adapted to provide a path for the passage of a needle therethrough, and having three or more slots formed therein extending from the needle hole in radiating relation to said hole.

2. A needle plate according to claim 1 having prongs defined by said slots.

3. A needle plate according to claim 2 wherein said prongs are located between the slots, said prongs having rounded-off, free inwardly directed ends within the plane of the needle plate.

4. A needle plate according to claim 1 having prongs located between the slots, wherein the needle hole is enlarged in the direction of the underside of the needle plate to form a recess in the underside of the plate.

5. A needle plate according to claim 2 wherein the needle hole is framed by the free ends of the prongs and is enlarged in the direction of the underside of the needle plate to form a recess in the underside of the plate.

6. A needle plate according to claim 2 adapted for use with a thread spreader having threads in contact therewith, wherein the prongs are disposed so that one thereof always is aligned with a line which extends, during the entrance of the needle into the needle plate, from the point at which the spreader acts on the threads through the path of the needle.

7. A needle plate according to claim 3 adapted for use with a thread spreader having thread in contact therewith, wherein the prongs are disposed so that one thereof always is aligned with a line which extends, during the entrance of the needle into the needle plate, from the point at which the spreader acts on the threads through the path of the needle.

8. A needle plate according to claim. 4 adapted for use with a thread spreader having threads in contact therewith, wherein the prongs are disposed so that one thereof always is aligned with a line which extends, during the entrance of the needle into the needle plate, from the point at which the spreader acts on the threads through the path of the needle.

9. The combination with the needle plate of claim 1 of a presser foot having a needle guide hole formed therein and disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle thereby to be effective in guarding against bending of the needle.

10. The combination with the needle plate of claim 1 of a presser foot having a needle guide hole formed therein and disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle and a frusto-cone portion leading thereto thereby to be effective in facilitating entry of the needle in the needle plate needle hole and in guarding against bending of the needle.

11. The combination with the needle plate of claim 2 of a presser foot having a needle guide hole formed therein and disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle thereby to be eifective in guarding against bending of the needle.

12. The combination with the needle plate of claim 2 of a presser foot having a needle guide hole formed therein disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter slightly greater than the diameter of the needle and a frusto-cone portion leading thereto thereby to be effective in facilitating entry of the needle in the needle plate needle hole and in guarding against bending of the needle.

13. The combination with the needle plate of claim 3 of a presser foot having a needle guide hole formed therein disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle thereby to be effective in guarding against bending of the needle.

14. The combination with the needle plate of claim 3 of a presser foot having a needle guide hole formed therein and disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle and a frusto-cone portion leading thereto thereby to be effective in facilitating entry of the needle in the needle plate needle hole and in guarding against bending of the needle.

15. The combination with the needle plate of claim 2 of a presser foot having a needle guide hole formed therein and disposed in centered relation directly over the needle plate needle hole, and a needle mounted for movement in the needle guide hole and plate needle hole, said needle guide hole including a portion which is cylindrical and of a diameter only slightly greater than the diameter of the needle and a frusto-cone portion leading thereto thereby to be effective in facilitating entry of the needle in the needle plate hole and in guarding against bending of the needle, and further characterized in that the needle plate needle hole is framed by the free ends of the prongs and said hole is enlarged in the direction of the underside of the needle plate to form a recess in the underside of the plate.

References Cited by the Examiner UNITED STATES PATENTS 983,343 2/1911 Bayer 112-227 1,325,365 12/1919 McCollum 1l2-260 X 3,131,660 5/1964 Idomoto l12-260 JORDAN FRANKLIN, Primary Examiner.

G. H. KRIZMANICH, Assistant Examiner. 

1. A NEEDLE PLATE FOR CHAIN STITCH SEWING MACHINES HAVING A NEEDLE HOLE FORMED THEREIN ADAPTED TO PROVIDE A PATH FOR THE PASSAGE OF A NEEDLE THERETHROUGH, AND HAVING THREE OR MORE SLOTS FORMED THEREIN EXTENDING FROM THE NEEDLE HOLE IN RADIATING RELATION TO SAID HOLE. 